Fuel Mileage Comparison: 1970 Cadillac and 1973 Mercedes

As I've always said, comparing magazine road tests can be very informative. Something interesting I noticed when I was going through my old car magazines. Car and Driver road tests of a 1970 Cadillac Eldorado and a 1973 Mercedes 450 SLC (April, 1970 and June, 1973). The fuel mileage figures are very close, even though the Cadillac has a much bigger engine and is over 1,000 lbs heavier. Here is the actual data:

Nice to see Cadillac hasn't changed much. 376ci instead of 472, supercharged instead of N/A, but the power is close. 550ft/lbs (gross) vs 551ft/lbs(net), 400hp (gross) vs 556hp (net). Twice as many gears, 600lbs difference, but the economy is basically the same.

MKBoyardee:Jesus, there are cars these days that weigh way more than that Caddy and have less power, yet still smoke it to 60 mph.

Don't forget that the Caddys numbers are measured in gross and now we use Net. Thats about a 20% difference. 400 gross hp is only about 320 net. Plus it has economy gears, and a vacuum controlled transmission, which hurts it.
..2011 Cadillac CTS-V Black Diamond EditionJust your average 650hp "luxury" sedan

MKBoyardee:Jesus, there are cars these days that weigh way more than that Caddy and have less power, yet still smoke it to 60 mph.

11secJeepSRT8:Don't forget that the Caddys numbers are measured in gross and now we use Net. Thats about a 20% difference. 400 gross hp is only about 320 net. Plus it has economy gears, and a vacuum controlled transmission, which hurts it.

Yes, you would have to factor in gross vs net hp. Also, wheelspin (1970s-era tires) and a 3.07:1 axle ratio is a long way from being an ideal ratio for running 1/4 mile times. Something like 3.70:1 would help a lot.
___________________Cars owned: '69 Cadillac Fleetwood, '76 Cadillac Limousine, '95 Lincoln Town Car- - - - - - - - - -MSNBC... the actual "faux news"

Young guy question which may or may not be stupid: Didn't the Clean Air Act of 1970 screw with all of the cars in the early 70's by putting choking emissions and having unleaded gas at a lower octane? I thought by '73/'74 most of the muscle cars and big engines were already way down on power and some big engine offerings like the 426 Hemi were already gone. If that is the case, that could explain some of the difference from a '70 Caddy vs. a '73 Mercedes.

I know Caddy offered big engines well into the 70's though, as a friend of mine had a '77 Caddy Sedan de Ville w/ a 425 in it, but it never seemed powerful at all.
...---..."I've got an idea so smart my head would explode if I even knew what I was talking about!"-Peter Griffin

ktkof09:Young guy question which may or may not be stupid: Didn't the Clean Air Act of 1970 screw with all of the cars in the early 70's by putting choking emissions and having unleaded gas at a lower octane? I thought by '73/'74 most of the muscle cars and big engines were already way down on power and some big engine offerings like the 426 Hemi were already gone. If that is the case, that could explain some of the difference from a '70 Caddy vs. a '73 Mercedes.

I know Caddy offered big engines well into the 70's though, as a friend of mine had a '77 Caddy Sedan de Ville w/ a 425 in it, but it never seemed powerful at all.